Hi again Ken,
After more closely examining your logfile I think I may have found the cause of the issue. It was caused by the reasons I stated previously that concerned the variation in hardware vendors' implementations of the OpenGL specification and I believe I have a fix that will properly accommodate the particulars of your system's graphics hardware. I will email you a link to a new version of PixelCNC which you can test out ASAP.
You don't need to worry about sending a new logfile just yet. Expect the link email soon if you haven't received it by the time you're reading this.